Integrated heat pump and water heating circuit

ABSTRACT

An integrated heat pump and water heating circuit for space heating and cooling and heating domestic water. The circuit includes a first heat exchanger for the domestic water, a second heat exchanger for the source (heat source/sink) with a first dedicated expansion valve, and a third exchanger for the space with a second dedicated expansion valve. The circuit has four modes of operation. In the first mode, the space is cooled and heat is rejected to the source. In the second mode, the space is heated while heat is absorbed from the source. In the third mode, the circuit absorbs heat from the source and heats the water supply. In a fourth mode, the water supply is heated and the space is cooled simultaneously. In each mode, one heat exchanger is inactive, and the charge from the inactive heat exchanger is reclaimed to the suction side of the compressor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No. 61/614,070 entitled “Integrated Heat Pump and Water Heating Circuit,” filed Mar. 22, 2012, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to heating, ventilation, and air conditioning methods and systems and, more particularly but without limitation, to heat pump systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with this description, serve to explain the principles of the invention. The drawings merely illustrate preferred embodiments of the invention and are not to be construed as limiting the scope of the invention.

FIG. 1 is a schematic diagram of an integrated heat pump and water heating circuit constructed in accordance with a first preferred embodiment of the present invention. The bolded line illustrates the refrigerant flow path when the system is operating in a first space cooling only mode.

FIG. 2 is a schematic diagram of the circuit of FIG. 1 illustrating the refrigerant flow path when the system is operating in a second space heating only mode.

FIG. 3 is a schematic diagram of the circuit of FIG. 1 illustrating the refrigerant flow path when the system is operating in a third water heating only mode.

FIG. 4 is a schematic diagram of the circuit of FIG. 1 illustrating the refrigerant flow path when the system is operating in a fourth mode in which the space is cooled and the domestic water supply is heated simultaneously.

FIG. 5 is a schematic diagram of an integrated heat pump and water heating circuit constructed in accordance with a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Modern space heating and cooling systems are increasingly improving in efficiency decreasing the energy used to condition buildings. As this energy use is reduced, other energy using items, specifically heating domestic water, become an increasingly large part of the building's energy usage. One promising approach to reduce building energy consumption is through a single integrated heat pump system to condition the space and heat the domestic water. The energy benefits of this system stem from the ability to utilize otherwise wasted energy; for example, heat rejected by the space cooling operation can be used for water heating.

The present invention comprises a refrigeration circuit that has four modes of operation: cooling a space, heating a space, heating water, and simultaneously cooling a space while heating water. Furthermore, the improved refrigeration circuit is designed such that passive charge control is provided by reclaiming charge from the inactive heater exchanger to the suction side of the compressor along with minimizing valves required for proper operation in any of the four modes.

Turning now to the drawings in general and to FIG. 1 in particular a first preferred embodiment of the circuit of the present invention will be described. The circuit, designated generally by the reference number 10, includes a compressor 12 and a plurality of heat exchangers interconnected in a conduit assembly 14. The compressor 12 includes an inlet 16 on the suction side and an outlet 18 on the discharge side. The compressor 12 circulates refrigerant through the circuit 10.

The plurality of heat exchangers includes a first heat exchanger 20 fluidly connectable to the structure's domestic water supply. The water supply heat exchanger 20 is operable as a condenser to heat the water supply. In most instances, the water supply heat exchanger will be a refrigerant-to-water heat exchanger.

Also included is a second heat exchanger 22 fluidly connectable to the heat pump's source. As used herein, “source” refers to a source such as water or air that serves as a heat sink or heat source. The source heat exchanger 22 is operable alternately as an evaporator and a condenser to selectively reject heat to or absorb heat from the source. In most instances, the source heat exchanger will be a refrigerant-to-water heat exchanger and the source will be water. However, other types of heat exchangers may be substituted. For example, for an outside air source, the heat exchanger may be a refrigerant-to-air type.

A first one-way expansion valve preferably is included in the conduit assembly 14 and is dedicated to the source heat exchanger 22, that is, it serves only the source heat exchanger.

The first expansion valve is positioned to meter refrigerant only entering the source heat exchanger 22 and only when it is operating as an evaporator. In the embodiment of FIG. 1, the expansion valve comprises an electronic expansion valve 24 and a check valve 26. The electronic expansion valve 24 meters refrigerant only when the heat exchanger 22 is operating as an evaporator and otherwise remains completely closed. The check valve 26 allows unrestricted flow of refrigerant in the direction opposite to that of the one-way expansion valve.

Referring still to FIG. 1, the refrigerant circuit 10 includes a third heat exchanger 30 fluidly connected to the space in the structure “S” to heat and cool the space. Thus, the space heat exchanger 30 is operable alternately as an evaporator and a condenser. In most instances, the space heat exchanger will be a refrigerant-to-air heat exchanger. However, other types of heat exchangers may be substituted. For example, for a radiant type heating system, the heat exchanger may be a refrigerant-to-water type.

A second one-way expansion valve preferably is included in the conduit assembly 14 and is dedicated to the space heat exchanger, that is, it is positioned to meter refrigerant only entering the source heat exchanger 30 and only when it is operating as an evaporator. In this embodiment, the expansion valve comprises an electronic expansion valve 34 and a check valve 36. The electronic expansion valve 34 meters refrigerant only when the heat exchanger 30 is operating as an evaporator and otherwise remains completely closed. The check valve 36 allows unrestricted flow of refrigerant in the direction opposite to that of the one-way expansion valve.

A desuperheater 40 may be included in the circuit 10. The desuperheater 40 is fluidly connectable to the domestic water supply and may be a refrigerant-to-water heat exchanger.

The conduit assembly includes conduits connecting the various components of the circuit 10. A discharge line 46 connects the compressor 12 to the desuperheater 40. The outlet of the desuperheater 40 is connected to the inlet port of a diverter valve 48. One port of the diverter valve 48 connects to one side of the water supply heat exchanger 20 through the conduit 50. Another port of the diverter valve 48 connects via the conduit 54 to the inlet port of a reversing valve 56. The fourth port of the diverting valve 48 is connected to the suction line 58 by means of the conduit 64.

One port of the reversing valve 56 connects to the suction line 58 to the inlet 16 of the compressor 12 through the conduit 66 and the three way coupling 68. Another port of the reversing valve 56 connects to the space heat exchanger 30 by the conduit 72. The fourth port of the reversing valve 56 connects to the source heat exchanger 22 by the conduit 74.

The conduit 80 connects the source heat exchanger 22 to the space heat exchanger 30. A conduit 82 connects the water supply heat exchanger 20 to the conduit 80 through the three way coupling 84.

Now it will be apparent that the preferred refrigerant circuit 10 includes an assembly of valves in the conduit assembly 14 configured to direct refrigerant between the compressor 12 and the heat exchangers 20, 22, 30, and 40. The valve assembly is configured to selectively direct the refrigerant in four different paths to provide four operating modes. The four modes of operation include a first space-cooling-only mode, a second space-heating-only mode, a third water-heating-only mode, and a fourth mode in which the water supply is heated and the space is cooled simultaneously. To that end, the preferred valve assembly includes the previously described diverter valve 48, the reversing valve 56, and the check valves 26, 36 and 90. The one-way expansion valves 24 and 34 also participate in directing the refrigerant according to the four modes. The operation of these valves to achieve the four different operating modes now will be explained.

The first flow path for the refrigerant through the circuit 10 is illustrated in FIG. 1 by the thicker lines. This flow path provides the first mode, that is, the mode in which only cooling of the space is provided. Refrigerant fluid leaving the compressor outlet 18 through the discharge line 46 passes through the desuperheater 40, where heat can be rejected to the domestic water. From the desuperheater 40, fluid enters the diverter valve 48. The diverter valve 48 directs the refrigerant through the conduit 54 to the reversing valve 56, which then routes it to the source heat exchanger 22 through the conduit 74, where heat is rejected to the source.

Fluid leaving the heat exchanger 22 passes through the conduit 80 to the space heat exchanger 30. In this path, the high pressure fluid passes through the check valve 26, bypassing the expansion valve 24, which is closed, and entering the expansion valve 34, as the check valve 36 is closed to flow in this direction. The refrigerant is metered in the expansion valve 34 prior to entering the heat exchanger 30, which in this mode is operating as an evaporator, absorbing heat from the space to cool the space.

Refrigerant vapor exits the heat exchanger/evaporator 30 and flows to the reversing valve 56 through the conduit 72. The reversing valve 56 in turn directs the fluid through the conduit 66 into the suction line 58 of the compressor 12. Now it will be apparent that the expansion valves 24 and 34 act also as directional valves to route the refrigerant through the circuit as well as to meter the refrigerant as it enters an evaporator. It should also be noted that in this mode condensed refrigerant is prevented from entering the hot water heat exchanger 20 by the check valve 90. At the same time, the water supply heat exchanger 20, which is inactive in this mode, is reclaimed as the diverter valve 48 opens the exchanger 20 to the suction line 58 through the conduits 50 and 64. Therefore, any refrigerant present in the water supply heat exchanger 20 will be evaporated and pulled back into the active refrigerant circuit for proper operation.

Turning now to FIG. 2, the second mode of operation will be described. In this mode, the space is heated. In this flow path, the compressor 12 discharges high-pressure refrigerant vapor through conduit 46 to the desuperheater 40, where heat can be rejected to the domestic water. The fluid passes from the desuperheater 40 to the diverter valve 48 and then to the reversing valve 56 from which is routed to the space heat exchanger 30 through the conduit 72. In this mode, the heat exchanger 30 is operating as a condenser to heat the space “S.”

High-pressure liquid then leaves the space heat exchanger 30 in the conduit 80 bypassing the expansion device 34, which is closed, and passing through the check valve 36 instead. From here, the fluid passes through the expansion valve 24, the check valve 26 being closed to flow in this direction. Expanded low-pressure refrigerant is metered into the source heat exchanger 22, which in this mode is operating as an evaporator, absorbing heat. Refrigerant vapor exits the heat exchanger 22 and passes to the reversing valve 56 through the conduit 74 and then to the suction line 58 through the conduit 66. As in space cooling mode, liquid refrigerant is prevented from entering the water supply heat exchanger 20 by the check valve 90. In this mode, the heat exchanger 20 is inactive, but this heat exchanger is reclaimed to the suction line 58 of the compressor 12 through the conduits 50 and 60 and the diverter valve 48, thereby providing proper refrigerant charge control.

With reference now to FIG. 3, the third mode of operation will be described. In this mode, the circuit 10 is used to heat the domestic water supply. The compressor 12 discharges high-pressure refrigerant vapor through the desuperheater 40, and is directed by the diverter valve 48 to the water supply heat exchanger 20 through the conduit 50. High-pressure liquid, having rejected heat to the water supply, leaves the heat exchanger 20 through the conduit 82 and passes through the check valve 90, open in this direction, into the conduit 80.

The electronic expansion device 34 is closed in this mode, so the fluid is routed through the expansion valve 24 and metered into the source heat exchanger 22, which in this mode is operating as an evaporator, absorbing heat from the water source.

Refrigerant vapor exits the heat exchanger 22 through the conduit 74 and is returned to the compressor 12 through the reversing valve 56, which directs the fluid into the conduit 66 and suction line 58. In this mode, liquid refrigerant is prevented from entering the space heat exchanger by check valve 36 and closed electronic expansion valve 34. In this mode, the space heat exchanger 30 is inactive, but it is reclaimed to the suction line 58 of the compressor 12 through the conduits 72, 54, and 64 and valves 48 and 56 so as to maintain proper refrigerant charge control.

To simultaneously cool the space and heat water, the refrigerant circuit 10 is operated in the mode depicted in FIG. 4. The compressor 12 discharges high-pressure refrigerant vapor through the desuperheater 40 and then to the diverter valve 48. The diverter valve 48 directs the fluid to the water supply heat exchanger 20 through the conduit 50, where heat is rejected to the structure's water supply. High-pressure liquid then leaves the water supply heat exchanger 20 and travels through check valve 90 in the conduit 82 to the expansion device 34, where it is metered into a low-pressure liquid traveling to the space heat exchanger 30, where it evaporates, absorbing heat from the space.

Refrigerant vapor exits the space heat exchanger 30 and flows through the conduit 72 to the reversing valve 56 from which it is returned to the compressor suction line 58 through the conduit 66. During this mode of operation, the source heat exchanger 22 is inactive, and liquid refrigerant is prevented from entering this heat exchanger by the check valve 26 and the electronic expansion valve 24, which is closed. Thus, the source heat exchanger 22 is reclaimed to the suction line 58 of the compressor 12 through the conduit 74 and 66 and the reversing valve 56 to insure proper refrigerant charge control.

FIG. 5 illustrates another embodiment of the refrigerant circuit present invention, which is designated generally by the reference number 10A. In this figure, no flow path is highlighted, as it will function similarly in the same modes as previously described. In this embodiment, the circuit 10A comprises the same compressor 12, domestic water heat exchanger 20, source heat exchanger 22, and space heat exchanger 30. Similarly, the valve assembly of this embodiment includes the same diverter valve 48 and reversing valve 56, as well as the check valves 26, 36, and 90. However, the desuperheater is omitted. Additionally, the electronic expansion valves 24 and 34 in the previous embodiment each have been replaced with a mechanical expansion valve 24 a and 34 a. Since mechanical expansion valves may not close tightly and typically will allow some reverse migration of refrigerant, each of the mechanical expansion valves is coupled with a solenoid shut-off valve 24 b and 34 b. Still further, a capillary tube or restrictor 40 is included in the conduit 64 between the diverter valve 48 and the suction line 58 of the compressor. This device restricts the amount of refrigerant entering the suction line 58 of the compressor 12.

In accordance with the method of the present invention, air conditioning and water heating is provided to a structure, wherein the structure has a heat pump source, a water supply, and a space to be cooled and heated. The method comprises selectively circulating refrigerant in a single refrigerant circuit, wherein the refrigerant circuit comprises a plurality of heat exchangers and a compressor interconnected by a conduit assembly. The step of circulating the refrigerant includes directing refrigerant selectively through four different fluid paths to provide four operating modes including a first space-cooling-only mode, a second space-heating-only mode, a third water-heating-only mode, and a fourth mode in which the water supply is heated and the space is cooled simultaneously.

The embodiments shown and described above are exemplary. Many details are often found in the art and, therefore, many such details are neither shown nor described herein. It is not claimed that all of the details, parts, elements, or steps described and shown were invented herein. Even though numerous characteristics and advantages of the present inventions have been described in the drawings and accompanying text, the description is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of the parts within the principles of the inventions to the full extent indicated by the broad meaning of the terms of the attached claims. The description and drawings of the specific embodiments herein do not point out what an infringement of this patent would be, but rather provide an example of how to use and make the invention. Likewise, the abstract is neither intended to define the invention, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. Rather, the limits of the invention and the bounds of the patent protection are measured by and defined in the following claims. 

What is claimed is:
 1. A heat pump and water heating circuit for a structure, wherein the structure has a heat pump source, a domestic water supply, and an space to be cooled and heated, the circuit comprising; a compressor having an inlet and an outlet; a plurality of heat exchangers comprising: a first heat exchanger fluidly connectable to the structure's domestic water supply, the first heat exchanger operable as a condenser to heat the water supply; a second heat exchanger fluidly connectable to the heat pump's source, the second heat exchanger being operable alternately as an evaporator and a condenser to selective reject heat to or absorb heat from the source; a third heat exchanger fluidly connected to the space, the third heat exchanger being operable alternately as an evaporator and a condenser to selectively cool or heat the space; a conduit assembly fluidly connecting the compressor and the plurality of heat exchangers to form a refrigerant circuit; a first one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the second heat exchanger and only when the second heat exchanger is operating as an evaporator; and a second one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the third heat exchanger and only when the third heat exchanger is operating as an evaporator; and a valve assembly in the conduit assembly configured to direct refrigerant between the compressor and the heat exchangers selectively in four different paths to provide four operating modes including a first space-cooling-only mode, a second space-heating-only mode, a third water-heating-only mode, and a fourth mode in which the water supply is heated and the space is cooled simultaneously.
 2. The heat pump and water heating circuit of claim 1 further comprising a desuperheater between the outlet of the compressor and the plurality of heat exchangers, wherein the desuperheater is fluidly connectable to the structure's domestic water supply.
 3. The heat pump and water heating circuit of claim 1 wherein the each of the first and second expansion valves comprises an electronic expansion valve operable between a metering position in which refrigerant is metered into the heat exchanger and a closed position in which flow through the expansion valve is blocked, and wherein the valve assembly includes a check valve for each expansion valve configured to allow fluid to bypass the expansion valve.
 4. The heat pump and water heating circuit of claim 1 wherein each of the first and second expansion valves comprises a mechanical expansion valve and a solenoid shut-off valve, and wherein the valve assembly includes a check valve for each expansion valve configured to allow fluid to bypass the expansion valve.
 5. The heat pump and water heating circuit of claim 1 wherein the valve assembly comprises a diverting valve and a reversing valve.
 6. The heat pump and water heating circuit of claim 1 wherein in any of the four modes of operation one of the plurality of heat exchangers is inactive and wherein the conduit assembly and the valve assembly are configured to direct refrigerant from the inactive heater exchanger to the suction side of the compressor whereby the charge from the inactive heater exchanger is reclaimed.
 7. The heat pump and water heating circuit of claim 1 wherein the heat pump source is a water source.
 8. A method for providing air conditioning and water heating to a structure, wherein the structure has a heat pump source, a domestic water supply, and a space to be cooled and heated, the method comprising: selectively circulating refrigerant in a single refrigerant circuit, wherein the refrigerant circuit comprises a plurality of heat exchangers and a compressor interconnected by a conduit assembly, and wherein the circulating step includes directing refrigerant through four different fluid paths to provide four operating modes including a first space-cooling-only mode, a second space-heating-only mode, a third water-heating-only mode, and a fourth mode in which the domestic water supply is heated and the space is cooled simultaneously.
 9. The method of claim 8 wherein the refrigerant circuit further comprises a desuperheater between the outlet of the compressor and the plurality of heat exchangers and wherein the desuperheater is fluidly connectable to the structure's water supply.
 10. The method of claim 8 wherein the plurality of heat exchangers in the refrigerant circuit includes: a first heat exchanger fluidly connectable to the structure's domestic water supply, the first heat exchanger operable as a condenser to heat the water supply; a second heat exchanger fluidly connectable to the heat pump's source, the second heat exchanger being operable alternately as an evaporator and a condenser to selective reject heat to or absorb heat from the source; and a third heat exchanger fluidly connected to the space, the third exchanger being operable alternately as an evaporator and a condenser to selectively cool or heat the space.
 11. The method of claim 10 wherein the refrigerant circuit further comprises: a first one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the second heat exchanger and only when the second heat exchanger is operating as an evaporator; and a second one-way expansion valve in the conduit assembly positioned to meter only refrigerant entering the third heat exchanger and only when the third heat exchanger is operating as an evaporator.
 12. The method of claim 11 wherein each of the first and second expansion valves comprises an electronic expansion valve operable between a metering position in which refrigerant is metered into the heat exchanger and a closed position in which flow through the expansion valve is blocked, and wherein the valve assembly includes a check valve for each electronic expansion valve configured to allow fluid to bypass the expansion valve.
 13. The method of claim 11 wherein each of the first and second expansion valves comprises a mechanical expansion valve and a solenoid shut-off valve, and wherein the valve assembly includes a check valve for each expansion valve configured to allow fluid to bypass the expansion valve.
 14. The method of claim 8 wherein the refrigerant circuit further comprises a valve assembly in the conduit assembly, and wherein valve assembly comprises a diverting valve and a reversing valve.
 15. The method of claim 8 further wherein in any of the four modes of operation one of the plurality of heat exchangers is inactive and wherein the method further comprises reclaiming charge from the inactive heater exchanger to the suction side of the compressor. 